He found access to King Wei 齊威王 (r. 378-343) as a member of the state-founded Jixia Academy 稷下, where he mastered the teachings of Guan Zhong 管仲 and Yan Ying 晏嬰 and studied the ancient rites as well as the "modern" administrative and penal law. He was therefore appointed grand master (dafu 大夫).

Chunyu Kun was an eloquent disputer who did not shy away from criticizing King Wei for his indulgence in nightly banquets. He admonished the King to care better for this duty in government and to see to it that Qi might become a strong state. Chunyu Kun discussed political matters with Zou Ji 鄒忌 and advocated administrative reforms.

When the state of Chu 楚 attacked Qi, Chunyu Kun was sent out to seek help from the king of Zhao 趙. The joint armies of Qi and Zhao were able to repell the invaders of Chu.

Later on Chunyu Kun traveled to the state of Wei 魏. King Hui of Wei 魏惠王 (better known as King Hui of Liang 梁惠王, r. 371-335) offered him the post of chief counsellor (xiang 相), but Chunyu Kun refused. He therefore never held an official appointment. Chunyu Kun had written a book called Wangduji 王度記, of which only sparse fragments have survived.